Polyacetal polymers are known in the art. Likewise, the use of glass fibers as reinforcing materials is known in the art. When glass fibers are used to reinforce polyacetal polymers, glass-matrix adhesion can be by means of chemical coupling agents, which form chemical bonds between the glass surface and polymer matrix. These coupling agents along with surface modifiers collectively referred to as sizing materials are added to the glass usually during its manufacturing. In simple terms, the glass is said to have been treated with a sizing material(s).
Silane compounds and/or derivatives are generally used as sizing materials. For polyacetal glass blends, azidosilane compounds are typically used as the coupling component of the glass fibers. However, the degree of adhesion produced by this combination is not sufficient to permit its utilization in certain applications which require maximum strength and stiffness. Thus, there exists a need for a reinforced polyacetal compound having improved fiber-matrix adhesive strength.
It is known in the art that the relatively modest strength of fiber reinforced polyacetal is a result of the relatively low reactivity of this polymer towards available coupling agents. Other thermoplastic polymers matrices such as polyamides are more reactive than polyacetal. This low reactivity of polyacetal polymers can be overcome by using the teachings of this invention.
In a nutshell, these teachings of this invention include the use of a known polymer, polyvinyl phenol, in a novel application involving the modification of the polyacetal matrix so as to enhance its adhesion to glass fibers.
Thus, it is a discovery of this invention that the addition of polyvinyl phenol to a polyacetal-glass fiber blend results in a compatible composition having improved adhesive strength.